As disclosed in U.S. Pat. No. 4,439,617 (Sestanj et al.), European Patent Application No. 0107930 (Cale et al.), and Scheeren et al., Synthesis, 1973, pp. 149-151, it is known that carbonyl compounds can be converted to the corresponding thiono compounds by reaction with tetraphosphorus decasulfide (more commonly, though less accurately, known as phosphorus pentasulfide). Scheeren et al. teach that improved results can be obtained by conducting such thiations in the presence of sodium bicarbonate and a polar solvent, and they also teach that their improved process is believed to be accomplished by a mechanism which would require the presence of their polar solvent.